From: Nikita Zhandarovich Date: Thu, 16 Jan 2025 13:48:01 +0000 (-0800) Subject: drm/repaper: fix integer overflows in repeat functions X-Git-Tag: v6.15-rc1~120^2~14^2~22 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=4d098000ac193f359e6b8ca4801dbdbd6a27b41f;p=thirdparty%2Flinux.git drm/repaper: fix integer overflows in repeat functions There are conditions, albeit somewhat unlikely, under which right hand expressions, calculating the end of time period in functions like repaper_frame_fixed_repeat(), may overflow. For instance, if 'factor10x' in repaper_get_temperature() is high enough (170), as is 'epd->stage_time' in repaper_probe(), then the resulting value of 'end' will not fit in unsigned int expression. Mitigate this by casting 'epd->factored_stage_time' to wider type before any multiplication is done. Found by Linux Verification Center (linuxtesting.org) with static analysis tool SVACE. Fixes: 3589211e9b03 ("drm/tinydrm: Add RePaper e-ink driver") Cc: stable@vger.kernel.org Signed-off-by: Nikita Zhandarovich Signed-off-by: Alex Lanzano Link: https://patchwork.freedesktop.org/patch/msgid/20250116134801.22067-1-n.zhandarovich@fintech.ru --- diff --git a/drivers/gpu/drm/tiny/repaper.c b/drivers/gpu/drm/tiny/repaper.c index 52ba6c699bc8f..5c3b51eb0a97e 100644 --- a/drivers/gpu/drm/tiny/repaper.c +++ b/drivers/gpu/drm/tiny/repaper.c @@ -456,7 +456,7 @@ static void repaper_frame_fixed_repeat(struct repaper_epd *epd, u8 fixed_value, enum repaper_stage stage) { u64 start = local_clock(); - u64 end = start + (epd->factored_stage_time * 1000 * 1000); + u64 end = start + ((u64)epd->factored_stage_time * 1000 * 1000); do { repaper_frame_fixed(epd, fixed_value, stage); @@ -467,7 +467,7 @@ static void repaper_frame_data_repeat(struct repaper_epd *epd, const u8 *image, const u8 *mask, enum repaper_stage stage) { u64 start = local_clock(); - u64 end = start + (epd->factored_stage_time * 1000 * 1000); + u64 end = start + ((u64)epd->factored_stage_time * 1000 * 1000); do { repaper_frame_data(epd, image, mask, stage);